參數(shù)資料
型號： LP3958
廠商： National Semiconductor Corporation
英文描述： Lighting Management Unit with High Voltage Boost Converter
中文描述： 照明管理股高電壓升壓轉(zhuǎn)換器
文件頁數(shù)： 8/28頁
文件大?。?/td> 1091K
代理商： LP3958
Power-Up Sequence
When powering up the device, V
and V
should be
greater than V
DDIO
to prevent any damage to the device.
20175576
Magnetic Boost DC/DC Converter
The LP3958 Boost DC/DC Converter generates an 8…18V
supply voltage for the LEDs from single Li-Ion battery
(3V…4.5V). The output voltage is controlled with an 8-bit
register in 10 steps. The converter is a magnetic switching
PWM mode DC/DC converter with a current limit. Switching
frequency is 1MHz, when timing resistor RT is 82k
. Timing
resistor defines the internal oscillator frequency and thus
directly affects boost frequency and KEY timings.
EMI filter (R
and C
) on the SW pin can be used to
suppress EMI caused by fast switching. These components
should be as near as possible to the SW pin to ensure
reliable operation. The LP3958 Boost Converter uses pulse-
skipping elimination to stabilize the noise spectrum. Even
with light load or no load a minimum length current pulse is
fed to the inductor. An active load is used to remove the
excess charge from the output capacitor at very light loads.
Active load can be disabled with the EN_AUTOLOAD bit.
Disabling active load will increase slightly the efficiency at
light loads, but the downside is that pulse skipping will occur.
The Boost Converter should be stopped when there is no
load to minimise the current consumption.
The topology of the magnetic boost converter is called CPM
control, current programmed mode, where the inductor cur-
rent is measured and controlled with the feedback. The user
can program the output voltage of the boost converter. The
output voltage control changes the resistor divider in the
feedback loop. The following figure shows the boost topol-
ogy with the protection circuitry. Four different protection
schemes are implemented:
1.
Over voltage protection, limits the maximum output volt-
age
— Keeps the output below breakdown voltage.
— Prevents boost operation if battery voltage is much
higher than desired output.
2.
Over current protection, limits the maximum inductor
current
— Voltage over switching NMOS is monitored; too high
voltages turn the switch off.
3.
Feedback break protection. Prevents uncontrolled op-
eration if FB pin gets disconnected.
4.
Duty cycle limiting, done with digital control.
20175577
Boost Converter Topology
L
www.national.com
8
相關(guān)PDF資料
PDF描述
LP3958TL Lighting Management Unit with High Voltage Boost Converter
LP3958TLX Lighting Management Unit with High Voltage Boost Converter
LP3971 POWER MANAGEMENT UNIT FOR ADVANCED APPLICATION PROCESSORS
LP3971SQ-A514 POWER MANAGEMENT UNIT FOR ADVANCED APPLICATION PROCESSORS
LP3971SQ-B410 POWER MANAGEMENT UNIT FOR ADVANCED APPLICATION PROCESSORS
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LP3958TL 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Lighting Management Unit with High Voltage Boost Converter
LP3958TL/NOPB 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N
LP3958TLX 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Lighting Management Unit with High Voltage Boost Converter
LP3958TLX/NOPB 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N
LP395Z 功能描述:兩極晶體管 - BJT RoHS:否 制造商:STMicroelectronics 配置: 晶體管極性:PNP 集電極—基極電壓 VCBO: 集電極—發(fā)射極最大電壓 VCEO:- 40 V 發(fā)射極 - 基極電壓 VEBO:- 6 V 集電極—射極飽和電壓: 最大直流電集電極電流: 增益帶寬產(chǎn)品fT: 直流集電極/Base Gain hfe Min:100 A 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PowerFLAT 2 x 2
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